Various load sensors are proposed in, for example, JP 10-39045A and U.S. Pat. No. 7,162,344 (JP 2005-153556A). According to these load sensors, a plurality of sensor cells is arranged like a matrix and occupies a region not less than one-half of all the seat surface of a seat of a vehicle. Electrodes are interposed between a pair of films.
In these load sensors, however, the pair of films occupy large areas. Therefore, formation of the pair of films is expensive. Besides, of the films, a rectangular portion on which the sensor cell is arranged and a portion that connects to the connector are narrowly formed. If a plurality of films is cut out of a large base film material, therefore, the peripheries of the connection portions are wasted. That is, in forming the film, a drop in the yield of the base film material results in an increase in the cost.